Friday, March 13, 2009

Oh, really? Hanna Rosin in the Atlantic makes the case against breastfeeding

Hanna Rosin's new article in the Atlantic follows a script that one commonly sees in reporting about nutrition science.

We have the headline boldly claiming that everything you thought you knew is overturned ...

The Case Against Breast-Feeding

... and the mild claim, buried in the middle, that defeats only a straw dummy (formula is not as menacing as smoking).

So overall, yes, breast is probably best. But not so much better that formula deserves the label of “public health menace,” alongside smoking.

We have the belittling of important results, whose main defect seems to be disagreement with the author's story line.

Kramer followed 17,000 infants born in Belarus throughout their childhoods. He came up with a clever way to randomize his study, at least somewhat, without doing anything unethical. He took mothers who had already started nursing, and then subjected half of them to an intervention strongly encouraging them to nurse exclusively for several months. The intervention worked: many women nursed longer as a result. And extended breast-feeding did reduce the risk of a gastrointestinal infection by 40 percent. This result seems to be consistent with the protection that sIgA [an element of breastmilk] provides; in real life, it adds up to about four out of 100 babies having one less incident of diarrhea or vomiting.

And I think we may have an instructive misunderstanding or misquoting of some statistical results.

Rosin quotes one fascinating study by Evenhouse and Reilly that compares cross-sectional analysis (showing how different breastfeeding practices for children in different families are related to different outcomes) to a within-family fixed effects analysis (showing how different breastfeeding practices for children in the same family are related to different outcomes). The fixed effects analysis has an important advantage, by controlling for confounding characteristics of the family. The fixed effects analysis also has an important disadvantage, lower precision (much bigger standard errors) because there are fewer mothers who change breastfeeding practices for different siblings.

Because of the lower precision (bigger standard errors), the same estimate of the effect of breastfeeding -- such as the finding that breastfed children are lighter or brighter -- could be "statistically significant" in the cross-sectional analysis and "statistically insignificant" in the fixed effects analysis. The important thing to do, in such cases, is to look at the actual estimates to see if they are much different in the two analyses.

If I am understanding Evenhouse and Reilly's analysis correctly, the cross-sectional estimates showed the usual benefits of breastfeeding for many outcomes. The fixed effects estimates agreed fairly closely on most of these outcomes, but were statistically insignificant because of larger standard errors.

For one key cognitive function score (PVT score), even the fixed effects analysis found a benefit of breastfeeding. So, Evenhouse and Reilly, in their summary, have good things to say about breastfeeding.

The significant correlation between breastfeeding and PVT score in our within-family model provides more credible evidence of a causal link between breastfeeding and cognitive ability than do existing nonexperimental studies. The effect is large enough to matter, and it is lasting, persisting into adolescence. Stronger evidence of causality may argue for intensifying breastfeeding promotion, particularly among groups that suffer from high rates of academic failure and other problems that some researchers have correlated with lower IQ (e.g., incarceration, poverty, or welfare recipiency). Some of the same social problems that justify additional expenditures on education and Head Start, for example, may also warrant additional efforts to raise breastfeeding rates.

Our results also suggest, however, that many of the other long-term effects of breastfeeding have been overstated.

How does Rosin describe what these authors say?

Almost all the differences turned out to be statistically insignificant. For the most part, the “long-term effects of breast feeding have been overstated,” they wrote.

Notice how Rosin quotes selectively from just part of Evenhouse and Reilly's last sentence. The rest would disagree with her story line.

22 comments:

What's heartening about this exchange (Hanna Rosin's article, and Parke Wilde's response) is that both sides are exceptionally informed and thoughtful. Parke Wilde is correct in his impressionistic assessment of our findings, and in underlining that statistical significance can fall victim to larger standard errors, with no real change in the point estimate. However, this is not to say that Hanna Rosin is wrong.

Hanna Rosin has an implicit null hypothesis: the benefits of breastfeeding are huge. It's not an unreasonable null, given attitudes to breastfeeding in the circles she moves in. And if one doesn't extrapolate beyond those circles (to the world's poor, for example, for whom formula feeding can be fatal), one can reasonably interpret the studies as failing to prove that the benefits are very, very large.

We began with a different null: the benefits of breastfeeding may be nil. And we made a pretty strong case that they are not, at least where cognition is concerned.

It's a glass half-full versus half-empty debate, complicated by the fact that our scientific view of the water level remains rather blurry.

Ours was a conservative approach. While our estimates may have understated or overstated the size of the beneficial effect of breastfeeding, a number of factors make it more likely that the effects were understated than the opposite. But if there is a statistical bias, it isn't one we can quantify, or expect commentators to infer.

If we thought that Hanna Rosin were in the pocket of the formula makers, we might read her piece differently. But we think she's raising an important point. The costs of breastfeeding, like so many of the costs of bearing and raising children, are difficult to measure, often staggeringly large, and borne almost entirely by parents (frequently, solely by mothers). It is certainly important to have a careful measurement of the benefits, and to recognize that, just as there is harm done when they are understated, there is harm done when they are overstated.

We wonder whether the following would be ideas with which both Parke Wilde and Hanna Rosin might agree?1. Major research to convincingly measure the effects of breastfeeding is in order, and expense should be no barrier. The answers really matter.2. Careful study of the costs of breastfeeding, and who bears them is warranted.3. If breastfeeding is beneficial, more support for breastfeeding mothers is long overdue.4. Every mother is owed the best and fullest information upon which to base her breastfeeding decision, and respect and support for the choice she makes.

We are also very sympathetic to Hanna Rosin's perspective. American mothers deserve a clear cost-benefit analysis of breastfeeding, but where would they find that? Researchers have focused almost exclusively on its benefits, but its costs are no less real. Prescription drugs come with warnings about adverse side effects. Hanna Rosin's complaint is that the prescription to breastfeed, dispensed so freely and so forcefully, is seldom accompanied by candid discussion of the "side effects" borne by nursing mothers.

Eirik EvenhouseDept of Economics &Lokey Graduate School of BusinessMills College

The comment that "Hanna Rosin's complaint is that the prescription to breastfeed, dispensed so freely and so forcefully" is completely not true in my circle of friends and my experience.

I was there when the nurse asked my wife if she was planning on breastfeeding. There was no forcing or prescription given. What we did get was a bunch of coupons for formula. No one told us the benefits of breastfeeding.

I am also sympathetic to Rosin thinking that woman are not equal to men, but to blame that on breastfeeding is completely wrong.

Thank you for this. My own objection to her characterization of the data was that she discounts the research because it fails to distinguish between the act of breastfeeding (holding the baby close for several hours a day) and the milk itself. If her goal is to free mothers from those hours of baby duty, it doesn't matter where the benefit comes from.

Anyway, you're exactly right: if you went into this believing that formula was like secondhand smoke, you learned something new. Those of us who went into it believing that breastfeeding confers significant benefits learned only that Rosin is really really tired of breastfeeding.

Hanna Rosin did not quote from the wide body of literature on the risks of formula feeding. Breastfeeding is the normal state of feeding an infant. It confers no benefits --- it is the norm. The risks and costs of alternatives are what need to be assessed.

First, she uses sleight of speech to disparage a wide body of doctors who contributed to the American Academy of Pediatrics Policy Statement on Breastfeeding and the Use of Human Milk. She provides no evidence whatsoever to support her statement about these doctors have an agenda. Conflict of interest in the medical arena usually involve payments of large sums of money from those who have commercial interests to those who are making statements. No one pays doctors to make positive statements about breastfeeding.

Second, if you look at the American Academy of Pediatrics statements, she avoids the conditions for which there is solid evidence that there is an increased risk from formula use including bacterial meningitis, bacteremia, diarrhea, late onset sepsis in preterm infants, necrotising enterocolitis, urinary tract infections, and postneonatal mortality. Solid -- meaning lots of credible studies. Since I started an MHS at Hopkins in 1983 through completing a doctorate in Nutritional Sciences at Cornell in 1993, I literally read THOUSANDS of credible studies -- and there are tens of thousands out there. I have stacks of meta-analyses under my desk and I reach very different conclusions

What she tackles in her article one condition among the many conditions of the "suggestive" research that is very hard to prove. This is the realm of SIDS, asthma, diabetes I and II, overweight and obesity, hypercholesterolemia, Hogkins, lymphoma and leukemia. These conditions are multicausal. It is very easy to design a study poorly and not see results and very hard to design a good study to find the causal links because the many of the effects are modified by other effects.

But even if all of this suggestive research turns out to not be so suggestive, what about the solid research? And she did not even site the risks to women when they don't breastfeed.

Now, why is it that someone like Hanna Rosin with no science background at all can call into question what is a huge body of research by mentioning one little sideline of the many studies that show an increased risk of disease from use of formula? Does she have better qualifications than MDs that have no conflicts of interest that wrote the policy statement?

As for the economic analysis of a breastfeeding, the World Bank tried such an approach many years ago with their Disability Adjusted Life Years. I worked on the protein energy malnutrition section. This approach was deeply flawed in that there was no way to include the fact that some interventions provide multiple benefits. Those interventions that addressed a single disease showed up better than those that addressed many diseases and had multiple benefits because the economic models were inadequate to deal with multiple benefits.

In terms of the costs of breastfeeding, what we are really talking about is the costs of caregiving. Babies need contact and interaction. Breastfeeding is but one way to provide this while at the same time providing food. What unfortunately has happened during the years when women were discouraged from breastfeeding is that we adopted feeding modes that are unhealthy for infants. I would love to work with exclusively formula feeding mothers to assist them to do what I do with mothers that have had breastfeeding problems --- that is "mimic normal infant feeding" and "mimize risk". The culture has adopted unrealistic expectations for the frequency and length of infant feeding as well as the amount of interaction that is really needed. In the past, women were in communities where sharing of childrearing with close kin members was far more common. Woman also did their productive activities in close proximity to their children so the displacement to feed their infants while working was not as much of a problem. Now women are expected to do it all on their own and conduct their income generating activities in a separate environment from their infants. The segregation of mothers from their infants does come at a cost.

Finally, the real clincher that everyone forgets about is that we had a healthier alternative in the past. Wet nursing was acceptable and available. Your sister could feed your infant to give you a break and no one would bat an eyelash at the practice. Now, in our super sterile environment where we confuse an infant's normal food with yucky body fluids --- such an idea is usually met with shock and horror.

Yet, human donor milk has been shown in many studies to be less risky than formula.

As for her assumption that only formula feeders are given a hard time, I beg to differ. If you took a sample of 1000 women, I am dead certain that 100% of that sample would say that their infant feeding choice has been criticized, regardless of what choice they made. If you took a sample of 1000 women on any parenting issue, you would find the same results. BUT, there is a false equivalency in this statement. If you looked at the degree of negativity in the "criticism" you would find that the most negative, disgusting comments are reserved for women who nurse in public. There is a huge degree of Lactaphobia in the culture due to the sexualization of the breast. You would never get away with saying that African Americans, homosexuals, the elderly, Jews, Muslims or any other group would have to eat in the bathroom. Yet, routinely, women are told that the only place their infants can eat normally is in the bathroom.

Hanna Rosin doesn't have the credibility to debunk the vast body of literature that I have read with her brief skimming of a few choice articles. She merely follows formulaic rules for justifying a billion dollar industry that took away choice from women for several generations and wants to perpetuate myths the risks of their product.

A better analogy than smoking is diabetes. Would you give insulin to someone without diabetes? No. Would you tell someone with diabetes that they are just as healthy as someone without it? No. Would you hesitate to give insulin to someone with type I diabetes? No. Would you tell them it was poison. No. Would you try to get someone with type II diabetes to eat better and excercise? Yes. If they still needed insulin, would you give it to them? Yes. Would you still work to help them overcome barriers to diet and exercise? Yes. Would you call health care practitioners that spoke frankly about diabetes "fanatics" or "nazis"? No.

Most of the discussion of infant feeding is highly irrational and overly emotional.

In the meantime, I will continue to assist women with pragmatic solutions to mimic normal and minimize risks of feeding their infants tailored to their own specific situations.

"If we thought that Hanna Rosin were in the pocket of the formula makers, we might read her piece differently."

"We have the headline boldly claiming that everything you thought you knew is overturned"

I was skeptical while reading Rosin's piece because it is hugely controversial. This means, of course, a huge amount of publicity and attention for her.

Rosin is telling us that all those medical experts promoting breastfeeding are wrong. She, the nonscientist, is giving us the truth. If these medical experts were being paid a fortune by a massive breastfeeding industry, her article would be food-for-thought. The reality is, experts encourage breastfeeding because its benefits have been proven.

As for the costs of breastfeeding or having children in general, no one is forcing Western women today to bear children. This is a choice we make. It doesn't make sense to make a choice and then whine about what that choice is costing us.

I am in agreement with Brian as I was never pressured by strangers, or otherwise, to choose breastfeeding over formula.In fact, I was never even visited by a Lactation Consultant--the hospital where I delivered didn't have one on staff. Furthermore, whenever I did try to call one of the nurses for assistance the information and 'help' I was offered was minimal and misleading to say the least.There are many points in Rosin's article where I find disagreements. One that I will bring up here is the idea that breastfeeding is not free unless of course we consider a woman's time worth nothing. To that I pose the question: By those standards wouldn't formula feeding cost twice as much? If we are to factor in the cost of the product plus the cost of the mother's time, wouldn't it be far more inexpensive to breastfeed? I guess this only holds true if the mother is the one doing majority of the bottle feeding and sadly, one of the 'benefits' to formula feeding is that any Tom, Dick or Jane can feed your kid for you.

"I was skeptical while reading Rosin's piece because it is hugely controversial. This means, of course, a huge amount of publicity and attention for her."

She is making apparently "hugely controversial" claims, which happen, in faux-contrarian fashion, to support the social and economic status quo, while keeping in the background the fact that she herself has the luxury to be able to breast feed her third infant, as she and her husband have agreed she would do the previous two. Like someone who lives on the West Side of Manhattan pretending to sympathize with those who patronize the salad bars of restaurants in middle western shopping malls, while pretending to denounce the "sophisticated" taste of fellow West Siders (which she happens to share). So typical of what one reads in the Atlantic Monthly in columns by David Brooks and other neo-con propagandists.

"I guess this only holds true if the mother is the one doing majority of the bottle feeding and sadly, one of the 'benefits' to formula feeding is that any Tom, Dick or Jane can feed your kid for you."

Or, you know, the father/ co-parent. Having the baby's food in a bottle instead of in the mother's breast means that the mother doesn't always have to be the one doing the feeding. Parenting can become a more gender-equal enterprise instead of being "woman's work."

Gender equity should be the goal. What is not understood among many parents is that it is not the food that causes the bonding, it is the social interaction and skin to skin contact that occurs while feeding. Males can provide the skin to skin contact that is physiologically beneficial to the infant by placing the baby on their naked chest for soothing and sleeping, through bathing the baby and through infant massage. These things provide more of an oxytocin response for men than putting the milk in the bottle and feeding the baby.

I rented a pump and pumped milk everyday. My husband fed it to the baby at night, so I could go to sleep. Resorting to formula is not necessary to ensure gender equity. Of course, husbands can also feed solids later on and assist in many other ways. Breastfeeding is not the oppressor of women that Rosin is trying to make it out to be.

It is now happening in breastfeeding groups. Women are quitting because the news media allowed someone with no science backrground whatsoever to go on the air without a rebuttal with the very solid evidence that's there. To me, this speaks of media bias. The media will allows its own to make all sorts of claims without investigation. What researcher has that kind of access. At the very least, WNYC, the Atlantic, and the Today show should invite a member of the Academy of Breastfeeding Medicine or the AAP Committee on Breastfeeding and Human Milk, the International Lactation Consult Association, the US Breastfeeding Committee and La Leche League International to refute the skewing and omission of evidence.

For your interest, does Rosin's article seem indebted to Joan Wolf's position in this OpposingViews debate? Wolf is a political scientist in the Women's Studies program at Texas A&M. I have some of the same skeptical questions about Wolf's summary of the scientific evidence that I had about Rosin's article. The wisest lesson that I take from both Rosin and Wolf are that disadvantages of formula should be stated plainly rather than exaggerated, and mothers' own decisions weighing a balance of considerations should be supported.

All this talk of breastfeeding makes me nostalgic for having an infant in the house! Now, when our children (ages 6 and 8) get hungry, after a day when they have been out adventuring, they shovel in astonishing amounts of food by themselves. Sometimes, they help cook. Of course, I couldn't breastfeed them even in former times, but I do remember having them asleep on my chest as Susan Burger describes. Lacking the erudite terminology, I had never thought to call that feeling an "oxytocin response". :-) We just called it "joy."

"It is now happening in breastfeeding groups. Women are quitting because the news media allowed someone with no science backrground whatsoever to go on the air without a rebuttal with the very solid evidence that's there."

Hysterics aside, one would hope that you (and others) would apply this same sense of skepticism and even outrage to the fact that "the media" touts the opinions of non-experts in virtually every important topic. When is the last time you were outraged that a journalist with a degree in English wrote a prominent article on economics or international finance? When is the last time you were outraged that The View preaches to millions of women every day on medicine, politics, economics and social issues?

Hanna Rosin argues that women should return to formula-feeding their babies, and as per me that's right. Breast milk is the perfect food for your baby. Breastfeeding boosts your baby’s immune system, preventing and minimizing many sicknesses.